Floating roof or cover for liquid storage tanks



J. H. WIGGINS Dec. 22, 1953 FLOATING ROOF OR COVER FOR LIQUID STORAGE TANKS Filed Aug. 29, 1950 FIGZ.

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5 a MM H mm M N 0 I W bl n NH A D M w.

V, B F

F a 3 P Patented Dec. 22, 1953 OFFICE FLOATING ROOF OR COVER FOR LIQUID STORAGE TANKS John H. Wiggins, Chicago, Ill.

Application August 29, 1950, Serial No. 182,002

2 Claims. (01. 220--26) This invention relates to floating tank roofs of the particular kind that comprise a flexible deck portion surrounded by and attached to a rigid, annular-shaped member that constitutes the peripheral portion of the roof, and which is of such weight that it exerts a sufficient downward force or load on the peripheral part of the flexible deck portion to maintain said deck portion in an inclined position, sloping upwardly from the periphery towards the center of the roof, whereby gases on the underside of the roof have a natural tendency to flow towards a gas collecting chamber or gas outlet at the center of the roof.

The main object of my present invention is to provide a floating roof of the general type or kind above mentioned, that is equipped with a novel means of inexpensive construction for accurately controlling the shape or form assumed by the flexible deck portion of the roof when the roof is floating.

Another object of my invention is to provide a floating roof of the general type or kind previously referred to, that is equipped with a flexible Weather roof, which, in addition to preventing rain or snow, loads from collecting on the flexible deck portion of the roof, also efiectively prevents said deck portion from assuming such a shape or form, when the roof is floating, that pockets of gas will be trapped on the undersideof the roof at points between the periphery of the roof and the gas outlet or gas collecting chamber at the center of the roof. Other objects and desirable features of my invention will be hereinafter pointed out.

Figure 1 of the drawings is a fragmentary, vertical, transverse sectional view, showing my improved roof sustained by or resting upon the removable supporting structure inside of the tank on which the roof is built or fabricated;

In the accompanying drawings which illustrate my invention embodied in a floating roof or cover for a sewage processing apparatus, A designates the side wall of a tank that is adapted to hold sewage or any liquid substance that is being stored or processed, B designates the flexible deck portion of my improved roof which is constructed of metal plates fabricated in such a manner as to produce a substantially flat, limber diaphragm that is capable of flexing throughout the major portion of its area, 0 designates as an entirety an annular member of rigid construction and of relatively great weight, that surrounds and is attached to the peripheral part of said flexible deck portion so as to force said peripheral part downwardly into the liquid a sufficient distance to normally maintain the deck in an inclined position sloping upwardly and inwardly from its inner edge when the roof is floating on the liquid, D designates a gas collecting chamber at the center of the roof, formed by a vertically-disposed, tubular member 1, that is closed at its upper end and open at its lower end, so as to permit gases on the underside of the roof to flow freely into the gas collecting chamber D, 2 designates a gas aduction pipe leading out of said gas collecting chamber, and E designates a flexible weather roof arranged above the flexible deck portion B in spaced relation with sameand attached at its outer and inner edges to the upper end of the annular, peripheral member 0 and to the upper end of the center tubular member 1, respectively. Instead of being provided with a center tubular member having a diameter such as to produce a gas collecting chamber of considerable volume, the roof may be provided with any kind of a suitable center support for the weather roof at- I tached at its lower end to the flexible deck por- Figure 2 is a similar view of a small size roof embodying my invention, showing the position assumed by the flexible weather roof and the flexible deck portion when the roof is not floating, but instead, is supported by brackets on the side wall of the tank;

Figure 3 is a similar view of a large size roof embodying my invention, showing the peripheral portion of the roof resting on supporting brackets on the tank side wall and the central portion of the roof resting on a stationary supporting structure located at the center of the tank; and

Figure 4 is a similar view, showing the normal condition of my improved roof, i. e., floating on and supported by a liquid or semi-liquid substance in the tank of the apparatus.

tion, and also may be provided with an kind of a gas outlet that permits the escape of gases from the underside of the flexible deck portion of the roof.

The basic idea of my present invention consists in using the weight or load of the flexible weather roof E to control the shape or form of the flexible deck portion B when the roof is floating on the liquid in the tank, as shown in Figure 4, and prevent pockets of gas from becoming trapped on the underside of the roof, at points between the periphery of the roof and the gas outlet at the center of the roof. I attain this result by arranging numerous vertically-disposed, rigid posts or thrust member's F between the weather roof E and flexible deck portion B throughout the major area of said parts, as shown struoted'in varioustways withoutdepa t ngirom in the drawings. As previously stated, my invention contemplates the use of a, deck portion that is flexible and which is joined or attached at its periphery to a rigid, annular member or structure, which is of sufiicient weight to create a relatively great downward force or load at the peripheral edge of said deck portion, for the purpose of mairitaining isaid de'kyin ,Lan ji-incline'd positionfisloping upwardly and; inwardly tow-ards the center of the roof, and thereby enhance or induce aflow of gases on the underside of the roof tol wards or into a gas outlet or .gasacollecti-ng chamber in the roof. In other wordsfin such a rooiit i's I essential for efiicient operation, that the part of the flexible deck portion a be disposed in a higher horizontal -planethan the peripheral part of said deckportion, and that the intermediate limber part of said declczportion' lying between said two above mentioned parts be prevented from: fiexingsupwardlysand assuming such: a=shape or form fas-nto ftrap pockets ofzgas or impede-the flowvoigaseson then-underside of the roof; towards-Abe :point where gasesare in- :tended to;be 'collectedr -orr released from the :un-

dersideof "theroof; Insmycimprovedroof, the previously 1 mentioned rigid posts-or ,thrustinem- --bers F causethetweight on-load of theweather To'ofE-tobe applied to orexerted downwardly on -;the limber -.metaldiaphragm-"which constitutes V the 'flexible 1 deck rIQQItiQD Be at. enough points throughout a the ;-area pf 'saidadeck portion, .to -'counteract thei==tendency oi said-,limber metal f diaphragm 'to flex intorsuch ashape or form,- as

to trap pocketsroj rgas itherebyinsuring thatthe deck portion-B of the-root, when thereof-is floati-ng, will-bemaintainedin its prdeterminedshape -;or; formshowns-inEigure.- 4. ln addition tocontrolling the shape r dorm ofsthe "fieX-ible @deck =portionobthe-roof; the-postsbr thrust mernbers F also-maintainthe flexible weatheeroof; E in an I outwardlyanddownwardly inclined position that -insures -efficient drainage of same. nFAny upward flexing-oithe .deck.-;por;tien B,- produced by l the great uplift forcesotfithe buoyant .liquid,or.- -gases contactedpby said deck portion; enhances ,the drainage characteristicseofthe;weather roof and alsqincreases the -load thatfisrelied mpon -.to assist in -mairrtaini ng;-gthepredetermined-shape; or form offithe flexible-tleck .portion, due to: the :f act =-that :upward flexing ofpsaid deck portionis trans- -mitted --.;by-- -the; posts- F rdirectlyr- :to' ithe; sflexible weather root gin ar-direction tending -;to wflex the same and-lif-t-the annular, peripheralepon ---tion C of the root tOrWhiCh: thesperiphery-go-f the weatherr-roofi is attached. -Normally, ;the; posts -or thrust members will 2beetack-welded to; the flexi ble deck portion B ancl -weathereroofi E;= because -saiddeck -rportioneand weatherroof will 1 I bend locally: enough-:totakeucare. of 2 the rela- -tive rocking 'movement betweenj'saidethrustzmembers and the 'two *elements of the structure between which they are interposed, but if: desired, the weather: rootvand sflexiblerd'eck zportionrcan be provided with lugsfloined -bye pivotpins Z-utO the supper andr lower-ends: oftheethrustgqnem- "bers F. r V

= --The: rigid; rannular peripheral-portion Q of the roofto'which the periplreries Ofnthecweather roof Eiand deckrportionBzareeattachedrcansbexcom,

" the-ispirit cfimyflmIen-tion;v Itemamcpnsist of -.an V I annular'r'im flvwelded'; torthe meripheral edges ,of --saidweather roor= nd=decki=portion andgGQm ned irwithia -builtein loadqnembem Moi eencretethe. esiikeethatiseeastsonrmoldedemrsituiontmsaimirim 4 3 and interlocked with same by anchoring de= vices 5, or said peripheral portion may comprise an additional annular rim 3 arranged in concentric relation with the rim 3 on the interior 5 of same and interlocked with the load member 4, said additional rim 3 being attached to the peripheral part of the flexible deck portion B and zzbeiigg utilized'as a form n'leinbergin the operation pf' casting or -molding the concretebr other pourable material, that is employed to add weight and i-mpart rigidity to the peripheral portion C of the smote a El-fheefrdof'"is built or fabricated on a removable supportin g structure inside of the tank that is broken lines in Figure 1. If the roof lispfi relail vglxsniall diameter, it may be support- 'd'by brackets'fi' on the tank side wall when it is notarfloating, as shown in Figure 2, as the flexibility of the deck portion B and weather roof E permit the.,central portion of the roof to sag. LIL-desired, :drains 1, can be'.' fbui1t1 into" the. roof, as shown -insFigure .-2, so as .toQcarry rain water ,.oif- -the ,low point of the weather roof when the roofis, supported by .;the side wall brackets 16. In .a :roof of;r,elatively great diameter,, as shown in Eigure 3 ,itis preferable to support the roof, when it-is not iioati ngv on, liquid. in ,thetank, by Supporting brackets ,6 on the tank, side wall vtori which the peripheral portion of thefroo'f rests, andLa stationary sup-porting sjtrncturelite in T' the i tank Ion which the central portionof thereof rests. I-Ia ving thus described 1 my 1 invention, :what I claim as new and desire to securebyLett'ers-Patentis: 1,.A fioatingrooi1rfor liquid storage tanks, comspris g 51,, flexible de portion rtrmedfby. a sub- ,stantia lly i flat, lirnber diaphragm Q'that Tfl 'oatibn *the-iiqu din-t e an 5a rer call edisfpp flrt b Jar member at, thepen telgof then-00f attached .to 40 said deck portion and being open atits lower. end rsozthat gases on the underside of,- he,deck;por,tion -can :escape upwardly: into-said tubularmember, im at 1 l the peripheral nterlocked with ta rigid,

I h 3 01; molded onz said rim .so as to i 'th red he 1 or io ei e -ro t h ;-biw an!2.; qu d as ici i n et 1 au es edeckrer pne n rmal z s m n -i n o soit nesl nin upward y-and inw rd at wards the ecent re 0f {t ro ae exib mw ath r ro .a -ta hcdz t eau r en s fsa dzrimaand. t z-th fillppel'ffilldrqf the tu-bular memberat the;ccnterl of the roof and disposed s as to preventrrain, snow u-e ndthe like irom fallinjg; on;- said; deck portion,

m an :re fi ic di pcs di iri im rustm mbers interpcsed :betweenwthe deck ;;pcrtion and the iweather {I'OOfz s0 aasz to; @utilize; :the weight of the roof to :maintaiis'said :deck portionsin aipredetersci-minedsha eorrformgr-A floa ngroofiaforzliquid stora e tankm prising adiqexible; deck portion formed by a, subtantially fiat,;limbenzmetalqdiaphragm of circu- ;l'ar; form r anianinular zzmcmber surrounding vand 5 attached to said deck portion,;;s,aid-,annular'memw per -being -ofl such weight;asvtogcausesaid. deck 'portion-,to' assume: {an inclined, position, sloping ...-,upwardly and ;inwardly;-;from=1the, periphery towards the: center Qf-sthB. roof, 2. gas outlet lead- '70, jng-d-rflm approximatelythe center of the under- ;;s ide .of; sa-id; ,d eckeportion, a flexible -weather roof arrapged QVBIEaSfi-id vdeck portion and .lattache'd at 11138 periphery andscenterto parts-carried by .said eckgportione said {Weather rooisbeingsinclined downwardlygandgoutwardly from; its center; to-

wards its peripheral edge for the purpose described, and vertically-disposed, rigid posts interposed between said deck portion and weather roof for supporting said weather roof and using the weight or load of same to resist upward flex- 5 ing of said deck portion, the said annular member having a built-in load element constructed of concrete or the like, that is cast in situ and interlocked with said annular member.

JOHN H. WIGGINS. 10

References Cited in the file of this patent UNITED STATES PATENTS Name Date Number Number Name Date Bohnhardt Apr. 15, 1930 Wiggins Aug, 11, 1936 Fischer et a1. Sept. 6, 1938 Joor May 21, 1940 Hammeren Oct. 3, 1944 Wiggins Nov. 11, 1947 Prager et al Feb. '7, 1950 Orr et al Feb. 26, 1952 FOREIGN PATENTS Country Date Germany Oct. 17, 1931 

